Im looking at buying an 85 F-250 4x2 with the 6.9L in it. I've heard some bad things about those engines but what exactly is wrong with them? I'm not buying the truck to pull heavy loads with or anything. I've been looking for an 80-86 f-150/250 for about a yr and this is the 2nd one that I've come across that seems worth it. What should I look for on the truck? Anything in particular? It's got a 4 spd standard transmission in it also..

Thanks for any replies!

I have always like the 6.9 engine, they say that they have a problem with the coolant creating static that eats through the cylinder walls make it seem like a blown head gasket. Nothing to do at that point but sleeve the block (way expensive ). Simply check the engine oil for any indication of water and check the coolant for any oil contaminates, if that's all OK and you feel OK about the rest of the truck just flush and fill and add the required additive (ask ford dealer for the name ).

RUN!

I've torn apart more than my share, they are decent, better than the GM 6.2L/6.5L, but not by much.

The 7.3L (bigger 6.9L) are MUCH better.

ModMech is just about right.
The 6.9 was built by International. Some blocks had a problem with porous castings causing coolant leaks etc, but they tended to show up fairly early in the engine life, so chances are if this engine has not developed the problem by now, it won't happen.
These engines are good for 300,000 to 400,000 km. A truck that old may be high mileage by now and these engines are expensive to rebuild. Buy only a low mileage version and run away if its smoking when running.